Appendix AUNFCCC Inventories of Industrial Processes and Waste

INDUSTRIAL PROCESSES AND PRODUCT USE

The industrial processes and product use (IPPU) sector covers the greenhouse gas emissions resulting from various industrial activities that produce emissions not directly the result of energy consumed during the process and the use of man-made greenhouse gases in products (IPCC, 2006). Examples include the release of CO2 as a by-product of cement production and the use of fossil fuel (primarily natural gas) as a feedstock in ammonia production. The IPPU sector accounts for about 7 percent of total greenhouse gas emissions from Annex I countries (UNFCCC, 2008) and about 6 percent of total greenhouse gas emissions for non-Annex I countries (UNFCCC, 2005).

Carbon Dioxide

Carbon dioxide (CO2) is the most important greenhouse gas emitted by the IPPU sector, comprising about 69 percent of total emissions (in terms of CO2 equivalents) from the sector for Annex I countries (UNFCCC, 2005). The main sources of CO2 in this sector are the production of cement, lime, glass, ammonia, iron, steel, and aluminum. The calcination of limestone produces lime, which may then be combined with silica compounds to produce clinker (an ingredient of cement). Both processes result in CO2 emissions. Glass production emits CO2 during the melting and fusion of limestone, dolomite, and soda ash. The principal source of CO2 emissions from ammonia production is the steam reforming of natural gas (methane, CH4) to produce hydrogen (H2). Iron and steel production yields CO2 emissions through the use of metallurgical coke to convert iron ore to pig iron in a blast furnace. Similarly, CO2 is emitted during the smelting process from the use of carbon to reduce alumina to aluminum.

The CO2 emissions from mineral, chemical, and metal production can be estimated simply by applying appropriate emission factors to national-level production data. The major source of uncertainty in emissions from the mineral industry is typically the activity data (IPCC, 2006; EPA, 2008) because the chemistry of the processes involved is known. For cement production, CO2 emissions should ideally be estimated using national-level data on clinker production, the lime content of the clinker, and the fraction of lime from limestone. However, national statistics on cement and/or clinker production may not be complete for countries in which a substantial part of production comes from numerous small kilns, for which data are difficult to obtain. If clinker production data are not available, they are inferred from information on the quantities of cement produced (correcting for imports and exports) and the types and clinker fraction of the cement. For lime and glass production, CO2 emissions can be estimated using national-level data on the types and quantities of lime or glass produced (or, less preferably, total lime or glass production figures) and default emission factors. The key source of uncertainty for lime production is incomplete data; reported lime production statistics often omit nonmarketed lime production, potentially resulting in order-of-magnitude underestimates. For glass production, activity data uncertainties

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Appendix A
UNFCCC Inventories of Industrial Processes and Waste
INDUSTRIAL PROCESSES AND PRODUCT duce hydrogen (H2). Iron and steel production yields
USE CO2 emissions through the use of metallurgical coke to
convert iron ore to pig iron in a blast furnace. Similarly,
The industrial processes and product use (IPPU) CO2 is emitted during the smelting process from the
sector covers the greenhouse gas emissions resulting use of carbon to reduce alumina to aluminum.
from various industrial activities that produce emissions The CO2 emissions from mineral, chemical, and
not directly the result of energy consumed during the metal production can be estimated simply by applying
process and the use of man-made greenhouse gases in appropriate emission factors to national-level produc-
products (IPCC, 2006). Examples include the release tion data. The major source of uncertainty in emissions
of CO2 as a by-product of cement production and the from the mineral industry is typically the activity data
use of fossil fuel (primarily natural gas) as a feedstock (IPCC, 2006; EPA, 2008) because the chemistry of
in ammonia production. The IPPU sector accounts for the processes involved is known. For cement produc-
about 7 percent of total greenhouse gas emissions from tion, CO2 emissions should ideally be estimated using
Annex I countries (UNFCCC, 2008) and about 6 per- national-level data on clinker production, the lime
cent of total greenhouse gas emissions for non-Annex content of the clinker, and the fraction of lime from
I countries (UNFCCC, 2005). limestone. However, national statistics on cement
and/or clinker production may not be complete for
Carbon Dioxide countries in which a substantial part of production
comes from numerous small kilns, for which data are
Carbon dioxide (CO 2) is the most important difficult to obtain. If clinker production data are not
greenhouse gas emitted by the IPPU sector, compris- available, they are inferred from information on the
ing about 69 percent of total emissions (in terms of quantities of cement produced (correcting for imports
CO2 equivalents) from the sector for Annex I countries and exports) and the types and clinker fraction of the
(UNFCCC, 2005). The main sources of CO2 in this cement. For lime and glass production, CO2 emissions
sector are the production of cement, lime, glass, ammo- can be estimated using national-level data on the types
nia, iron, steel, and aluminum. The calcination of lime- and quantities of lime or glass produced (or, less prefer-
stone produces lime, which may then be combined with ably, total lime or glass production figures) and default
silica compounds to produce clinker (an ingredient of emission factors. The key source of uncertainty for lime
cement). Both processes result in CO2 emissions. Glass production is incomplete data; reported lime produc-
production emits CO2 during the melting and fusion of tion statistics often omit nonmarketed lime production,
limestone, dolomite, and soda ash. The principal source potentially resulting in order-of-magnitude underesti-
of CO2 emissions from ammonia production is the mates. For glass production, activity data uncertainties
steam reforming of natural gas (methane, CH4) to pro-

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APPENDIX A
are magnified where glass production is measured in a consumption of a chemical in a specific application or
variety of units. subapplication (production plus imports minus exports
In the chemical and metal industries, reliable pro- minus destruction of the chemical) and then applying
duction data are available for most countries, so the an emission factor(s) to the net consumption. For the
emission factors present the greatest source of uncer- mass-balance approach, emissions are estimated as
tainty, particularly for iron and steel production. For the sum of the sales of a chemical and, for equipment
ammonia production, CO2 emissions can be estimated containing this chemical, the total charge of retired
using national-level data on ammonia production (or, equipment minus the total charge of new equipment.
less preferably, ammonia production capacity) and The major source of uncertainty in national estimates of
default values for the quantity of fuel (typically natural HFC emissions is the lack of activity data on chemical
gas) required as feedstock per unit of output, the carbon production or sales in countries where suppliers treat
content of the fuel, and the carbon oxidation factor. the information as confidential. This barrier to the pro-
Any CO2 recovered for purposes of urea production duction of reliable national estimates is being reduced
is also accounted for. For iron and steel production, with the development of regional and global databases
the CO2 emissions are estimated by applying the of ozone-depleting substances. For example, databases
appropriate emission factors to national statistics on that track the phase-out of ozone-depleting substances
the amount of steel produced by each method and the are directly relevant for estimating the phase-in of HFC
total amount of pig iron produced that is not processed substitutes (IPCC, 2006).
into steel. Similarly, the estimation of CO2 emissions in Emissions of HFC-23 can be calculated by apply-
aluminum production requires national-level produc- ing a default emission factor to the quantity of HCFC-
tion data by process type (i.e., Søderberg or Prebake) 22 produced. Given the known variability in emissions
to which the appropriate default emission factor can from different HCFC-22 manufacturing facilities, the
then be applied. uncertainty in the emission factor far outweighs the
uncertainty in the activity data (IPCC, 2006).
Hydrofluorocarbons
Nitrous Oxide
Hydrofluorocarbons (HFCs) comprise about 18
percent of total emissions (in terms of CO2 equivalents) Emissions of nitrous oxide (N2O) from nitric acid
from the IPPU sector for Annex I countries.1 The use and adipic acid production comprise about 7 percent
of HFCs as substitutes for ozone-depleting substances of total emissions from the IPPU sector in Annex I
countries.2 Nitric acid production emits N2O as a by-
in a variety of industrial applications is by far the largest
source of HFC emissions, accounting for about 86 per- product during the catalytic oxidation of ammonia, and
cent of total emissions from the sector, and their usage adipic acid production (most of which takes place in a
is growing rapidly. A smaller, but significant source of few plants in the United States and Europe) generates
HFC emissions is the generation of trifluoromethane N2O as a by-product during a process involving the
(HFC-23) as a by-product during the production of oxidation of nitric acid. Emissions of N2O from both
chlorodifluoromethane (HCFC-22). sources can be estimated by multiplying production by
Actual emissions of HFCs are estimated using a default emission factor. For nitric acid production, the
either an emission-factor or a mass-balance approach major source of uncertainty in N2O emissions is the
(IPCC, 2006). Both methods can use activity data activity data. Nitric acid production is often underesti-
collected at either the application level (e.g., refrig- mated because nitric acid is formed as part of a larger
eration) or the subapplication level (e.g., equipment production process and is never sold on the market.
or product type); the latter is expected to yield higher- For adipic acid production, neither the default emission
accuracy estimates. For the emission-factor approach, factor nor the activity data are significant sources of
HFC emissions are calculated by determining the net uncertainty (IPCC, 2006). The default emission factor
1 See 2 See
. .

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APPENDIX A
is derived from a well-understood chemical reaction decades of historical data are required), although some
(i.e., nitric acid oxidation), and only a small number of of the emission factors can also be highly uncertain. For
adipic acid plants exist. many countries, data on waste amounts and composi-
tion (particularly historical data) are not available and
default activity data must be used. The major uncertain-
WASTE
ties in the emission factors include the DOC values
The waste sector is not a significant source of assigned to different waste types (e.g., municipal) and
greenhouse gas emissions, accounting for only about 3 materials (e.g., paper, food), the fraction of DOC that
percent of the total from Annex I countries (UNFCCC, is ultimately degraded and released from SWDS, and
2008) and about 4 percent of the total from non-Annex the half-life of the DOC, which is difficult to measure
I countries (UNFCCC, 2005). This sector covers the in real solid waste disposal sites. Also highly uncertain
greenhouse gas emissions from solid waste disposal, are the emission factors used to determine the frac-
biological treatment of solid waste, burning of waste, tion of CH4 that is oxidized in the landfill’s top layer,
and wastewater treatment and discharge (IPCC, 2006). which depends on whether the SWDS is managed or
Waste sector reporting includes neither the greenhouse unmanaged and also varies considerably with condi-
gas emissions resulting from the use of waste mate- tions at the site.
rial as fuel nor the CO2 emissions resulting from the The other significant source of CH4 emissions
decomposition or burning of organic biomass. These within the waste sector is the anaerobic treatment or
emissions are accounted for under the energy sector disposal of wastewater. The CH4 emitted from waste-
and the agriculture, forestry, and other land-use sector, water handling depends on the amount of degrad-
respectively. able organic material, measured by biological oxygen
demand in domestic wastewater and chemical oxygen
demand in industrial wastewater. The Intergovernmen-
Methane
tal Panel on Climate Change (IPCC) provides a means
The primary greenhouse gas emitted from the of estimating the quantity of domestic wastewater
waste sector is CH4, which accounts for about 90 generated as well as default values for biological oxy-
percent of the total (in terms of waste sector CO2 gen demand for selected regions and countries. Simi-
equivalents) in Annex I countries.3 The degradation larly, the IPCC provides default values for quantities
of organic material under anaerobic conditions at solid of industrial wastewater generated and the chemical
waste disposal sites (SWDS) is the principal source of oxygen demand for various industry types. Reliable
CH4 emissions. The potential of SWDS to generate estimates of the quantity of CH4 released from waste-
CH4 depends on the degradable organic carbon (DOC) water discharge are particularly difficult to obtain for
content of the waste, which is a function of the amount developing countries due to uncertainties in the frac-
and composition of the waste disposed, and on the tion of domestic wastewater that is removed by sewers
waste management practices. Methane emissions from (as opposed to being treated in latrines), the fraction
SWDS are calculated using the First Order Decay of sewers that are open, and the degree to which these
method, which assumes that the rate of CH4 produc- open sewers are anaerobic (IPCC, 2006).
tion is directly proportional to the amount of DOC
remaining in the waste. The quantity of CH4 that is Carbon Dioxide
oxidized in the landfill’s top layer and/or is recovered
and combusted is then subtracted from the calculated Carbon dioxide is a relatively minor source of
emissions value. g reenhouse gas emissions from the waste sector,
The key source of uncertainty in estimates of CH4 accounting for about 4 percent of total emissions (in
from SWDS is the activity data relating to the quanti- terms of CO2 equivalents) from the sector for Annex
I Parties.4 The predominant source of these emissions,
ties and composition of the waste disposed (several
3 See 4 See
. .

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APPENDIX A
comprising about 97 percent of total CO2 emissions effluent into aquatic environments are sources of N2O
from this sector, is the incineration and open burn- emissions, the latter is typically a far more significant
ing of waste containing fossil carbon (e.g., plastics, source. Emissions of N2O from wastewater effluent
certain textiles). The practice of waste incineration is discharged to aquatic environments are determined
currently more common in developed countries, while using national statistics on population and annual
open burning of waste occurs predominantly in the per capita protein consumption to estimate the total
developing world. However, the basic approach recom- amount of nitrogen discharged in wastewater effluent,
mended by the IPCC for estimating CO2 emissions and a default emission factor for the N2O emitted per
from these two sources is the same: the quantity of unit of wastewater effluent nitrogen content (IPCC,
waste incinerated and/or open-burned is multiplied by 2006). Large uncertainties are associated with estimates
default values for the dry matter content, total carbon of N2O emissions from wastewater handling, and the
content, fossil carbon fraction, and oxidation factor for major source of uncertainty is the default emission fac-
the waste (IPCC, 2006). The major source of uncer- tor for N2O from the effluent.
tainty is the estimation of the fossil carbon fraction
of the waste, which is directly related to uncertainties REFERENCES
regarding waste composition. Where country-specific
EPA (Environmental Protection Agency), 2008, Inventory of U.S.
data regarding quantities of waste incinerated and/or
Greenhouse Gas Emissions and Sinks: 0-00, EPA 430-R-
open-burned are not available, large uncertainties are 08-005, Office of Atmospheric Programs, Washington, D.C.,
also associated with the waste amounts determined available at .
IPCC (Intergovernmental Panel on Climate Change), 2006, 00
management.
IPCC Guidelines for National Greenhouse Gas Inventories, H.S.
Eggleston, L. Buendia, K. Miwa, T. Ngara, and K. Tanabe,
eds., prepared by the National Greenhouse Gas Inventories
Nitrous Oxide
Programme, Institute for Global Environmental Strategies,
Hayama, Kanagawa, Japan, 5 volumes.
Nitrous oxide emissions comprise about 6 percent
UNFCCC (United Nations Framework Convention on Climate
of total emissions (in terms of CO2 equivalents) from Change), 2005, Sixth compilation and synthesis of initial na-
the waste sector for Annex I countries.5 The major tional communications from Parties not included in Annex I to
the Convention, prepared by the UNFCCC Secretariat, October
source, comprising about 82 percent of total N2O emis-
2005, available at .
emitted from the degradation of nitrogen components UNFCCC, 2008, Report on national greenhouse gas inventory
in the wastewater (e.g., urea, nitrate, protein). Although data from Parties included in Annex I to the Convention for
the period 1990-2006, prepared by the UNFCCC Secretariat,
both wastewater treatment plants and the discharge of
November 2008, available at .
5 See .

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